SEED Infotech Pvt. Ltd. 1 Networking in Java. SEED Infotech Pvt. Ltd. 2 Objectives of This Session Describe issues related to any type of network using

SEED Infotech Pvt. Ltd.1

Networking in Java


Objectives of This SessionObjectives of This Session

Describe issues related to any type of network using OSI model

State what is a protocol

Describe the TCP/IP protocol

Describe the client-server concept with respect to Internet

State the features of http .

State the need for client side scripts

Identify the reasons for popularity of java as a client side script


Host based ProcessingHost based Processing

DataDataApplication

Logic

ApplicationLogicServer

Clients

Mainframe

Keystrokes

Terminal C

haracters

Terminal 1 Terminal 2 Terminal 3 Terminal 4


Client - ServerClient - Server

DBMSDBMS

Network Server

RequestsResults

Client Workstation 1

ApplicationLogic

ApplicationLogic

ApplicationLogic

ApplicationLogic

ApplicationLogic

ApplicationLogic

ApplicationLogic

ApplicationLogic

Client Workstation 2 Client Workstation 3 Client Workstation 4

ApplicationLogic

ApplicationLogic


Web Based ArchitectureWeb Based Architecture

INTERNETINTERNET

UNIX

WINDOWS

MACINTOSH

WEB SERVER

WEB SERVER

HTTPTCP/IP


ProtocolProtocol

• Protocols are rules and procedures for communication.

• Lays out the details of how a computer can send & receive data on a network.

• Protocols here govern:

Packaging of data into packets.

Speed of transmission.

Recreation of data to its original form.

Eg: of network protocols: TCP/IP, AppleTalk , NetBEUI etc


OSI (Open System Interconnection)ModelOSI (Open System Interconnection)Model

APPLICATION

PRESENTATION

SESSION

TRANSPORT

NETWORK

DATA LINK

PHYSICAL


The OSI LayersThe OSI Layers

7) Application: Provides different services to the applications

6) Presentation: Converts the information

5) Session: Handle problems which are not communication issues

4) Transport: Provides end to end communication control

3) Network: Routes the information in the network

2) Data Link: Provides error control between adjacent nodes

1) Physical: Connects the entity to the transmission media



Application Layer

• Provides different services to the applications

• Serves as a window for applications to access network services.

• Handles general network access, flow control and error recovery.



Presentation Layer

• Determines the format used to exchange data among the networked computers.

• Translates data from a format from the Application layer into an intermediate format.

• Responsible for protocol conversion, data translation, data encryption, data compression, character conversion, and graphics expansion.

• Redirector operates at this level.



Session Layer

• Allows two applications running on different computers to establish use and end a connection called a Session.

• Performs name recognition and security.

• Provides synchronization by placing checkpoints in the data stream.

• Implements dialog control between communicating processes.



Transport Layer

• Responsible for packet creation.

• Provides an additional connection level between the Session layer.

• Ensures that packets are delivered error free, in sequence with no losses or duplications.

• Unpacks, reassembles and sends receipt of messages at the receiving end.

• Provides flow control, error handling, and solves transmission problems.



Network Layer

• Responsible for addressing messages and translating logical addresses and names into physical addresses.

• Determines the route from the source to the destination computer.

• Manages traffic such as packet switching, routing and controlling the congestion of data.



Data Link Layer

• Sends data frames from the Network layer to the Physical layer.

• Packages raw bits into frames for the Network layer at the receiving end.

• Responsible for providing error free transmission of frames through the Physical layer.



Physical Layer

• Transmits the unstructured raw bit stream over a physical medium.

• Relates the electrical, optical mechanical and functional interfaces to the cable.

• Defines how the cable is attached to the network adapter card.


TCP/IP ArchitectureTCP/IP Architecture

APPLICATION LAYER

TRANSPORT LAYER

NETWORK LAYER

LINK LAYER


IP Addressing Scheme (IPV4)IP Addressing Scheme (IPV4)

Class IP Address Range

A 0.0.0.0 to 127.255.255.255

B 128.0.0.0 to 191.255.255.255

C 192.0.0.0 to 223.255.255.255

D 224.0.0.0 to 239.255.255.255

CLASSSES OF IP ADDRESSES

CLASS A

CLASS B

CLASS C

CLASS D

0 Net id Host id

10 Net id Host id

110 Net id Host id

1110 Multicast group id


TCP/IP ArchitectureTCP/IP Architecture

HTTP TFTP PingFTP Telnet DNSSMTP SNMP NNTP

TCP UDP

Internet Protocol (IP)

ICMP

ARP RARP

Ethernet, to ken Ring, RS232 ………


TCP protocolTCP protocol

• Provides communications in a heterogeneous environment.

• Routable, defacto standard for internetworking. • Connection oriented protocol.• Relies on IP for addressing & routing• Guarantees reliable delivery in the order in which

packets were sent.• E.g.’s of app’s that run on top of TCP:

FTP, TelNet, HTTP


UDP protocolUDP protocol

Connectionless protocol.

Relies on IP for addressing & routing

If you send datagram over a UDP protocol, it may not arrive, if it does, it may arrive out of order etc.

E.g.’s of app’s that run on top of UDP:

SNMP, TFTP


ServerServer

Applies to any program that offers a service that can be reached over a network.

Accepts a request over the network, performs its service & returns the result to the requester.

Usually servers are implemented as application prgs.


ClientClient

An executing program that sends a request to a server & waits for an response.

client Server

Request

Response


Client Side ScriptsClient Side Scripts

HTML

Javascript

VB script

Jscript

Applets

Documents

SEED Infotech Pvt. Ltd. 1 Networking in Java. SEED Infotech Pvt. Ltd. 2 Objectives of This Session Describe issues related to any type of network using